Analysis by: Alvin Bacani
ALIASES:

Backdoor:Win32/Tenpeq.gen!A (Microsoft); Trojan-Downloader.Win32.Agent.usfc (Kaspersky)

 PLATFORM:

Windows 2000, Windows Server 2003, Windows XP (32-bit, 64-bit), Windows Vista (32-bit, 64-bit), Windows 7 (32-bit, 64-bit)

 OVERALL RISK RATING:
 DAMAGE POTENTIAL:
 DISTRIBUTION POTENTIAL:
 REPORTED INFECTION:
 INFORMATION EXPOSURE:

  • Threat Type: Backdoor

  • Destructiveness: No

  • Encrypted: No

  • In the wild: Yes

  OVERVIEW

Infection Channel: Downloaded from the Internet, Dropped by other malware

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

It runs certain commands that it receives remotely from a malicious user. Doing this puts the affected computer and information found on the computer at greater risk.

  TECHNICAL DETAILS

File Size: 102,400 bytes
File Type: DLL
Memory Resident: Yes
Initial Samples Received Date: 26 Jul 2013

Arrival Details

This backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.

Installation

This backdoor adds the following mutexes to ensure that only one of its copies runs at any one time:

  • RKYuanKong

Other System Modifications

This backdoor adds the following registry entries:

HKEY_LOCAL_MACHINE\SOFTWARE\QQ\
QQNETPET
MasterDNSE = "{BLOCKED}.43.226"

HKEY_LOCAL_MACHINE\SOFTWARE\QQ\
QQNETPET
MasterPort = "80"

HKEY_LOCAL_MACHINE\SOFTWARE\QQ\
QQNETPET
NetPetName = {varies}

Backdoor Routine

This backdoor executes the following command(s) from a remote malicious user:

  • Download and execute file.
  • List file/services/process on the affected system
  • Monitor mouse and keyboard event.
  • Steal System information.
  • Update system settings.
  • Upload file/Delete file.

It connects to the following URL(s) to send and receive commands from a remote malicious user:

  • {BLOCKED}.43.226 via port 80

  SOLUTION

Minimum Scan Engine: 9.300
FIRST VSAPI PATTERN FILE: 10.184.07
FIRST VSAPI PATTERN DATE: 29 Jul 2013

Step 1

Before doing any scans, Windows XP, Windows Vista, and Windows 7 users must disable System Restore to allow full scanning of their computers.

Step 2

Scan your computer with your Trend Micro product and note files detected as BKDR_TENPEQ.OMU

Step 3

Restart in Safe Mode

[ Learn More ]

Step 4

Search and delete files detected as BKDR_TENPEQ.OMU

[ Learn More ]
Please make sure you check the Search Hidden Files and Folders checkbox in the More advanced options option to include all hidden folders in the search result.

Step 5

Delete this registry value

[ Learn More ]

Important: Editing the Windows Registry incorrectly can lead to irreversible system malfunction. Please do this step only if you know how or you can ask assistance from your system administrator. Else, check this Microsoft article first before modifying your computer's registry.

 
  • In HKEY_LOCAL_MACHINE\SOFTWARE\QQ\QQNETPET
    • MasterDNSE = "{BLOCKED}.43.226"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\QQ\QQNETPET
    • MasterPort = "80"
  • In HKEY_LOCAL_MACHINE\SOFTWARE\QQ\QQNETPET
    • NetPetName = {varies}

Step 6

Restart in normal mode and scan your computer with your Trend Micro product for files detected as BKDR_TENPEQ.OMU. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check this Knowledge Base page for more information.


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